topic Re: i.MX6 mfw_isink color quantization artifact "Posterization" in i.MX Processors

i.MX6 mfw_isink color quantization artifact "Posterization"

Tarek — Tue, 01 Jul 2014 12:59:19 GMT

Hi, I'm using mfw_isink on i.MX6D for displaying and resizing the video. The image contains several regions of colors instead of a continuous gradation of tone. The problem seams to be more obvious on wide surfaces like a ceiling or a wall.

This snapshot shows the color contours on the ceiling:

Is there away to reduce this effect?

My command line:

console=ttymxc3,115200 video=mxcfb0:dev=hdmi,1920x1080@60,bpp=32,if=RGB24 root=/dev/mmcblk0p1 rw rootwait rootfs=ext3 enable_wait_mode=off consoleblank=0 video=mxcfb1:off video=mxcfb2:off maxcpus=2 kmemleak=on

Thanks

Re: i.MX6 mfw_isink color quantization artifact "Posterization"

joanxie — Fri, 11 Jul 2014 09:12:04 GMT

how about changing the mfw_isink to mfw_v4lsink? isink has the worst performance than v4lsink, pls try it.

Re: i.MX6 mfw_isink color quantization artifact "Posterization"

Tarek — Fri, 11 Jul 2014 09:24:11 GMT

I have to use mfw_isink in my application. I need to play multiple streams simultaneously in addition to scaling and positioning all of which not supported by mfw_v4lsink. Actually this is why we are using i.MX6.

Is there another solution?

Re: i.MX6 mfw_isink color quantization artifact "Posterization"

Tarek — Wed, 23 Jul 2014 14:23:45 GMT

Another screenshot to show the problem:

i.MX6: "Please note the contours effect in the white area which dosn't exists in the second image"

PC software decoder "The white color grading is continuous ":

Can Freescale please explain such effect and how to improve it?

Re: i.MX6 mfw_isink color quantization artifact "Posterization"

Tarek — Tue, 05 Aug 2014 11:44:43 GMT

IPU team,

I have used SW decoder in order to identify whether it's IPU or VPU. This is my pipeline:

gst-launch-0.10 souphttpsrc location=$HTTP ! video/mpeg, mpegversion=4 ! typefind ! mpeg4videoparse ! ffdec_mpeg4 ! ffmpegcolorspace ! mfw_isink sync=true

I still see the same problem so I think it's most likely to be the IPU.

Can you please give us advise?

Thanks

Re: i.MX6 mfw_isink color quantization artifact "Posterization"

Tarek — Tue, 05 Aug 2014 14:40:35 GMT

To further narrow it down I used v4l_sink. It turned out that the problem is only when using mfw_isink.

Is there anyway to improve the situation?

Re: i.MX6 mfw_isink color quantization artifact "Posterization"

Tarek — Wed, 06 Aug 2014 14:08:38 GMT

I found the problem was /dev/fb1 bpp=16 and I wanted it to be 32.

The format in /usr/share/vssconfig was incorrect format = RGBP

and I changed it to format = ABGR

Now /dev/fb1 bpp=32 and the picture quality is fine.